Hydraulic pump or motor



Jall- 1955 L. E. BDNNETTE ET AL 2,

HYDRAULIC PUMP OR MOTOR 5. Sheets-Sheet 1 Filed Oct. 15, 1949 INVENTORS Ellis HQB orn Edward MM Culhugh E.Bonnette WM Jan. 11, 1955 7 Filed 00+; 15. 1949 E. BONNETTE ET AL 2,699,123 HYDRAULIC PUMP OR MOTOR s Sheets-Sheet 2 l 25 l-' 25 22 z? INVENTORS Ellis I-LBorn Edward. M. M0u11nugh FIG 5, Leroy E.B0nnette A TTORNE Y.

Jan. 1955 L. E. BONNETTE ET AL 2,699,123

HYDRAULIC PUMP OR MOTOR Filed Oct. 15. 1949 3' Sheets-Sheet 3 FIG-.5.

INVENTORS Ellis H. Born yEdwurdMMCuuouqh Leroy E.Bonnette MZOMVZWM United States Patent M HYDRAULIC PUMP 0R MOTOR Leroy E. Bonnette, Delaware, and Edward M. McCullough and Ellis H. Born, Columbus, Ohio, assignors to The Denison Engineering Company, Columbus, Ohio Application October 15, 1949, Serial No. 121,526

Claims. (Cl. 103-162) This invention relates generally to hydraulic apparatus and in its more particular aspects to mechanism for generating fluid pressure and translating the same into motion, the mechanism being in the form of an axial piston pump or motor.

One of the objects of the invention is to improve the efl'iciency and operating characteristics of the type of fluid pump or motor shown and described in the co-pending application of Ellis H. Born, Serial No. 697,042, filed September 14, 1946, now Patent No. 2,619,041 and assigned to The Denison Engineering Company.

Another object of the invention is to provide an axial piston pump or motor having reciprocating pistons and cam means for governing the operation of the pistons, the device having bearing shoes and a wear-distributing ring between the pistons and the cam means, whereby thedactive life of the device may be appreciably lengthene A further object of the invention is to provide an axial piston pump or motor having reciprocating pistons and cam means cooperating to effect the reciprocation of the pistons, there being anti-friction means between the pistons and the cam means, such anti-friction means including relatively movable bearing elements composed of dissimilar materials.

A still further object of the invention is to provide an axial piston pump or motor having a cylinder barrel with reciprocating pistons and a substantially circular flat surface cam disposed at an angle to the axis of rotation of the cylinder barrel, there being bearing shoes between the pistons and the cam means and a wear plate between the bearing shoes and the inclined cam, the wear plate being free to rotate relative to'the cam and the bearing shoes, there being means in the form of a hub on the cam, in the form of the invention illustrated, to cause the wear plate to rotate about an axis located eccentrically to the center of rotary movement of the bearing shoes on the wear plate, whereby the path traversed by the bearing shoes on the wear plate will be of a greater area than such path would be if the bearing shoes and the wear plate revolved about the same axis.

Another object of the invention is to so locate the axis about which the wear plate mentioned in the previous paragraph rotates that the force imparted thereto by the bearing shoes will tend to cause the rotation of the wear plate, rather than to permit the same to remain stationary.

Still another object of the invention is to provide the piston, the bearing shoes and the wear plate with communicating passages so that fluid being transmitted by the pump will be applied to the surfaces of the bearing shoes and wear plate between which relative movement takes place.

Another object of the invention is to provide an axial piston pump having movable means for varying the volume and indicating means for showing the degree of movement of the volume varying means, the indicating means being such that the degree of movement of the volume varying means will be multiplied on the indicator, thus rendering the indicator more sensitive.

Other objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal sectional view taken 2,699,123 Patented Jan. 11, 1955 through an axial piston pump formed in accordance with the present invention.

Fig. 2 is a detail horizontal sectional view taken on the planes indicated by the line II-II of Fig. 1.

Fig. 3 is a front elevational view of the cam plate with the wearing plate applied thereto.

Fig. 4 is a horizontal sectional view taken through the cam and wear plate on the plane indicated by the line lVlV of Fig. 3.

Fig. 5 is a diagrammatic view illustrating the relative positions of the wear plate and the inlet and outlet ports formed in the valve plate of the pump, and,

Fig. 6 is a diagrammatic view illustrating the mechanism for indicating the degree of movement of the volume varying means.

Referring more particularly to the drawings, the entire pump shown in section in Fig. 1 is designed generally by the numeral 20. The complete pump has been illustrated, although the invention pertains more particularly to the construction of the cam means for imparting rcciprocatory movement to the pump pistons and the other parts of the pump cooperating therewith. The pump will be generally described to facilitate an understanding of the invention.

The pump includes a casing 21 having a body 22, which is composed of sections 23, 24, and 25, a head 26 and a cap 27. These parts cooperate to form a chamber 23. In this chamber, there is provided a bearing 30 for rotatably receiving a cylinder barrel 31; the head 26 is also provided with hearing means 32 to form the rotatable mounting for a drive shaft 33, one end of the shaft extending in to the chamber 28 and being connected by splines, or, other driving means 34 with the cylinder barrel 31. The casing is also provided with a valve plate 35 in which arcuate inlet and outlet ports 36 and 37 are formed, these ports communicating with inlet and exhaust openings provided in the head 26. The cylinder barrel has one end thereof in sliding engagement with the valve plate, this end of the cylinder barrel having openings 38 for alternate registration with the arcuate inlet and outlet ports, the ports 38 communicating with cylinder bores 39 formed in the cylinder barrel. These cylinders receive pistons 40 for reciprocation therein, this movement of the pistons serving to draw fluid into the cylinder bores when the ports 38 are in registration with the inlet port and discharge fluid from the cylinders when the ports 38 are in registration with the outlet port.

To eifect this reciprocating movement of the pistons, the device is provided with a cam assembly designated by the numeral 41 and including a body 42, which is mounted for pivotal adjustment about an axis extending at right angles to the longitudinal axis of the shaft 33, suitable means being provided for effecting this movement of the body 42. The member 42 has a plate 43 of substantially circular form secured thereto, this plate being partially wedge-shaped as illustrated in Fig. 4, so that the front and rear surfaces 44 and 45 are disposed at an angle to one another.

In the pump selected for illustration, these surfaces are arranged at an angle of approximately 3 to one another. The surface 45 abuts the flat surface of the member 42, which surface is parallel with the axis of movement of the member 42 and thus disposes the surface 44 at an angle of 3 relative to such axis. This 3 angle extends substantially horizontally in the pump when such pump is disposed as illustrated in the drawing. When the pump is in this position, the inlet and outlet ports are arranged substantially symmetrically on opposite sides of a vertical axis passing through the axis of the shaft 33. It will be seen from the description thus far that an axis extending across the face of the plate 43 and the 3 angle relative to the rear surface of such plate will be disposed substantially horizontally in the pump at all times.

In one model of the invention, which has been found to operate successfully the member 42 has been formed from a cast material, for example, Meehanite, and the plate 43 has been formed from bearing bronze. This plate 43 has a hub 46 projecting therefrom, this hub being disposed at right angles to the surface 44 and having its axis offset relative to the axis or center of the plate 43. This relation is shown by small crosses at 64 and 65 in Figures 3 and 5 of the drawing.

in the form of the invention illustrated, the bearing plate 43 is attached to the member 42 by cap screws 48. The surface 44 of the plate 43 is highly polished to furnish a bearing for a wear plate 49, which in the successfully operating model was formed of steel, hardened and ground, to also provide smooth front and rear surfaces. This plate 49 is provided with a central opening to receive the hub 46 which will provide a bearing or journal for the steel wear plate. This plate also forms a surface with which bearing shoes 50 are adapted to engage. These bearing shoes which in the above-mentioned model were formed of bearing bronze, have a universal connection with substantially spherical heads 51 formed on the outer ends of the pistons 40, the bearing shoes having a socket connection and being clamped around the spherical head to be connected with the pistons, this connection providing for the transmission of pushing, as well as, pulling forces to the pistons. Each bearing shoe is formed with a projection, in which the socket for the ball is provided, this projection extending through an opening in a retainer plate 52, the projection being slightly smaller, than the bearing shoes, so that a flange will be provided, this flange being engaged by the retainer plate 52. The center of this plate is rormed with a spherical opening 53 to receive a ball 54 which is urged toward the plate by a spring pressed plunger 55 the force of this spring pressed plunger urges the retainer plate toward the cam means, the plate in turn holding the bearings shoes in engagement with the plate 49. As illustrated in Fig. l the bearing shoes have the surface in engagement with the plate 49 provided with a recess 56, which is connected by a passage 57 with the spherical socket. The pistons are each provided with a passage 58, which extends from the socket to the inner end of the piston and establishes communication between the cylinder bores and the sockets, the passages thus providing for the introduction of fluid from the cylinder bore to the recess 56 in the bearing shoe. The eflective area of the bearing shoes exposed to the pressure admitted to the recess 56 is limited by circular grooves 66) formed in the rear surfaces of the bearing shoes around the recesses 56. Grooves 60 are connected by one or more slots with the pump chamber 28; fluid thus escaping from the recess 56 will be admitted to the chamber 28.

It is also within the concept of the invention to provide a rear surface of the plate 49 with a plurality of recesses, corresponding to the recess 56 and being connected therewith, when any one of the shoes is substantially in registration therewith, by a passage 61 extending through the 5 plate 49. The area of the plate 49 exposed to pressure is limited in the same Way as the similar areas of the bearing shoes by an annular groove 62 extending around the recess in the plate, the groove 62 being in communication with the chamber 28 by one or more slots.

It should be obvious that as the shaft 33 is revolved, the cylinder barrel 31 will move likewise causing the pistons to revolve in a circular direction carrying with them the bearing shoes 50. Since these bearing shoes are held in engagement with the plate 49 which is disposed in an inclined position, the bearing shoes will slide on the plate 49 and cause the pistons 40 to move back and forth in the cylinder bores 39. This movement of the pistons will draw fluid into the cylinder bores and discharge the fluid therefrom. Due to the engagement of the shoes 50 with the plate 49 and the fact that the plate 49 is unrestrained against movement this plate will also be caused to revolve relative to the bearing plate 43. Since the bearing shoes are free to slide on the bearing plate 49, the latter will revolve at a different rate of speed than the rate at which the cylinder barrel is revolved. Due to the eccentric location of the center of rotation of the plate 49, the path traversed by the bearing shoes on such plate will possess a width greater than the diameter of one of the bearing shoes; the wear caused by the sliding movement of the bearing shoe on the wear plate will thus be distributed over a greater area of the plate.

This eccentric location is best illustrated in Fig. 5, wherein the wear plate is illustrated, by dotted lines, superimposed on the valve plate; two bearing shoes are also illustrated in dotted lines, as is also the hub 46. It will be noted from Fig. 5 that the bearing shoes are substantially in circular registration with the inlet and outlet ports 36 and 37. They will revolve about the axis of the valve plate, this axis being indicated by the numeral 64, while the plate 49 will revolve about the axis indicated by the numeral 65. When the bearing shoes are sub stantially in registration with the inlet port 36, one edge of the bearing shoes will coincide with one edge of the plate 49. When the shoes are substantially in registration with the outlet port 37, the edge of the shoe will be disposed adjacent the edge of the hub on which the plate 49 is pivoted. Since this plate is free to revolve, it will be obvious that the entire surface will be exposed to the wearing action of the shoes sliding thereon and the shoes will thus be prevented from wearing a path in the plate. blIlCC considerably more surface is exposed to the wearing action, the life of the wear plate will be appreciably lengthened. it will be noted also from Fig. 5, that the eccentric mounting of the wear plate 49 is disposed on the outlet side of the pump, this outlet side will receive more load during the operation of the pump and the force transmitted to the plate will have more tendency to cause movement of the plate. 1 ts rotation will thus be assured. Inasmuch as the path on the wear plate traversed by the bearing shoes is eccentric to the axis of the rotation of the wear plate, the plate will be caused to rotate at a diflerent rate of speed than the cylinder barrel. This difference in rates or rotation will insure a more uniform distribution of wear over the entire surface.

The present invention improves the pump illustrated from another standpoint since the pump illustrated is a variable volume pump in which the cam means may be ad usted from a position in which the cam track, or, plate is disposed substantially at right angles to the longitudinal axis of the rotor to one in which such cam surface is disposed at a relatively sharp angle to such axis.

it will be obvious that as the cam is moved from one extreme to the other, the path traversed by the bearing shoes will be changed, for example, if the cam is actually at right angles to the axis of rotation of the cylinder barrel, the path traversed by the bearing shoes will be circular. When the cam is moved to the extreme of its inclined adjustment, the path traversed by the bearing shoes will be an ellipse or oval. The longitudinal axis of this oval will be vertical. In changing from one extreme position to the other and causing the bearing shoes to engage other surfaces of the wear plate, it is essential that the cam surface thereof be perfectly smooth and flat, otherwise undue leakage between the bearing shoes and the cam surfaces will develop.

It has been found in actual practice that where bearing shoes are employed with a steel cam, the shoes will pick up minute particles of abrasive material in the fluid and cause the steel ca m to wear in the path engaged by the shoes, then when the cam is adjusted to vary the volume of the pump, the shoes will engage two surfaces having different levels thus creating a gap where fluid under pressure may escape. When the wear distributing plate is employed as illustrated in this application, the wear caused by such abrasive action is reduced to a minimum because of the relative movement of the wear plate and cam and is distributed over a greater area because of the eccentric location of the wear plate. The life of the apparatus is therefore lengthened and the efficiency of the device materially improved. By locating the axis of rotation of the wear plate eccentrically and disposing the lever arm caused by such eccentric location on the same side of the axial center of the pump as the high pressure or exhaust port, the wear plate is caused to rotate more effectively.

The wedge-shape of the plate 43 causes the wear plate 49 to be inclined transversely which inclination does not affect the pumping action of the device, but it is effective in decreasing the noise incident to the operation of the pump by causing an equilization of pressure between the cylinder bores and the ports approached thereby as the ports 38 move across the space between the inlet and outlet ports. This feature has been set forth in the abovementioned copending application. It is shown and claimed herein only to the extent of the combination of the inclination and the movable wear plate.

A novel form of indicating mechanism has been illustrated in Figures 2 and 6 of the drawings, this indicating mechanism being used to show the degree of movement of the volume varying mechanism of the pump. This indicating mechanism includes a dial 70 which is mounted on the exterior of the pump casing and a pointer 71 for movement relative to the dial, the pointer being carried by a pivot 72 journalled in the pump casing. This pivot is provided on its inner end with flat sides 73 for engagement with the sides of a slot 74 formed in a link 75. This link is pivotally supported on the volume varying member 42 which, as previously mentioned, is itself pivoted in the frame as at 76. It will be noted that the pin 72 is disposed in the casing between the pivot 76 for the volume bearing member and the pivot 77 for the link 75. As illustrated by dotted lines in Fig. 6, the swinging movement of the member 42 about the pivot 76 will cause movement of the pivot 77 in an arcuate path. It will also be obvious that link 75 will move with the pivot 77 at the end attached thereto, while the opposite end will impart rotary movement to the pin 72, which is journalled at a stationary point. It will be obvious from the dotted line illustration in Fig. 6, that the degree of rotation of the pin 72 as indicated by the pointer 71 will be materially greater than the degree of rotation of the member 42 about the axis 76. A relatively small amount of movement of the volume varying member will thus be made apparent by the indicating mechanism.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

We claim:

1. A fluid pressure energy translating device comprising a casing with inlet and outlet ports; a valve plate in said casing with arcuate ports communicating with said inlet and outlet ports; a cylinder barrel having one end in rotary sliding engagement with said valve plate, said barrel having ported cylinder bores alternately communicating with said inlet and outlet ports upon rotary movement of said barrel; pistons disposed for reciprocation in the cylinder bores in said barrel; cam means for reciprocating said pistons during rotary movement of said barrel, said cam means having a substantially fiat, stationary bearing face inclined in one direction relative to the axis of rotation of said cylinder barrel; a hub projecting from said bearing face, the axis of said hub being normal to the plane of said face, a disk member journalled on said hub and engaging said face; means for adjusting said cam means to vary the inclination of said bearing face; and bearing shoe means between said pistons and said disk member; said bearing shoes being in sliding engagement with said disk.

2. In a fluid pressure energy translating device a relatively movable rotor and cam assembly; pistons disposed for movement in said rotor by said cam assembly, said cam assembly comprising a member with a stationary flat bearing surface disposed at an angle to the axis of rotation of said rotor; a hub projecting from said bearing surface, the axis of said hub being disposed in a plane at one side of the axis of rotation of said rotor; a wear plate positioned for free rotary motion on said hub; and bearing shoes universally connected with the pistons in said rotor and engaging said wear plate.

3. In a fluid pressure energy translating device a cylinder barrel mounted for rotation about an axis; pistons disposed for reciprocation in said cylinder barrel; bearing shoes on the pistons in said cylinder barrel; a cam construction for controlling the movement of the pistons in said cylinder barrel comprising a support mounted for rocking movement about an axis extending at right angles to the axis of rotation of said cylinder barrel, said support having a surface parallel to the axis of movement of said support; a member mounted on said support in engagement with said surface, said member having a flat bearing surface disposed at an acute angle to the axis of movement of said support and the first-mentioned surface; and a disk-like element journalled for free rotary motion on said member in engagement with said flat bearing surface, said bearing shoes being disposed in sliding engagement with said disk-like element.

4. In a fluid pressure energy translating device, a cylinder barrel mounted for rotation about an axis; pistons disposed for reciprocation in said cylinder barrel; bearing shoes on the pistons in said cylinder barrel; a cam construction for controlling the movement of the pistons in said cylinder barrel comprising a support mounted for rocking movement about an axis extending at right angles to the axis of rotation of said cylinder barrel, said support having a surface forming a stationary bearing; a disk-like element disposed in engagement With said bearing surface; and means supporting said disk-like element for free rotary motion about an axis disposed in a plane at one side of the axis of rotation of said cylinder barrel, said bearing shoes being disposed in sliding engagement with said disk-like element.

5. In a fluid pressure energy translating device, a relatively movable rotor and cam assembly; pistons disposed for reciprocation in said rotor by said cam assembly, said cam assembly comprising a support; means mounting said support for movement about an axis extending at right angles to the axis of said rotor; a flat bearing surface on said support, said surface being disposed in a plane extending at an acute angle to the axis of movement of said support; a disk journalled for free rotary motion in engagement with said flat bearing surface; and bearing shoes with flat bearing surfaces carried by the pistons in said rotor, the bearing surfaces on said shoes slidably engaging said disk.

References Cited in the file of this patent UNITED STATES PATENTS 1,632,304 Maurer June 14, 1927 2,069,651 Ferris Feb. 2, 1937 2,379,546 Snader et a1 July 3, 1945 2,430,764 Gabriel Nov. 11, 1947 2,433,222 Huber Dec. 23, 1947 2,483,856 Temple Oct. 4, 1949 2,518,618 Huber Aug. 15, 1950 2,525,498 Naylor et a1 Oct. 10, 1950 

